After Congress left cities to fend for themselves, four new cases -- possibly the first to be contracted by mosquitoes in the U.S. -- suggest how difficult it is for them to combat the virus on their own.

Congressional inaction on Zika funds has hampered efforts on the local level to stop the spread of the disease. That was more or less proven Friday when Florida Department of Health officials said it's highly likely that four new cases in Miami were the first to be contracted by infected mosquitoes in the U.S.

To date, there have been 1,658 cases of Zika in the continental United States. But so far, they've all involved someone who had traveled to a foreign country or had sex with someone who had recently been to a Zika-affected country.

President Obama in May proposed $1.9 billion to help combat the spread of the virus. Congress, however, was unable to agree on that number and left for recess without allocating any extra money for state and local governments.

Even if Congress does allocate Zika funding, local officials say they may already have missed an important window for combatting the virus.

“The real tragedy is that now is the time when you need the extra money and resources: July and August is mosquito control time all across the U.S.,” said Peter Hotez, dean of the National School of Tropical Medicine at the Baylor College of Medicine. “Everything from here on out is just going to be damage control.”

In the absence of federal funding, localities have been left to fend for themselves.

“The Centers for Disease Control is not going to fight this disease. This is going to be a fight almost exclusively at the local level,” said Hotez.

Beyond mosquito control, which is hardest in the summer months, Hotez says local health centers must start being constantly on the lookout for possible cases.